Enhanced Superconductivity in TiO Epitaxial Thin Films

TL;DR

This study reports the synthesis and characterization of epitaxial TiO thin films exhibiting superconductivity at a record Tc of 7.4 K, demonstrating the potential for higher-temperature superconductivity in epitaxial titanium oxides.

Contribution

First demonstration of epitaxial TiO films showing superconductivity with a Tc significantly higher than bulk, enabling systematic investigation of its properties.

Findings

TiO films are type-II superconductors with Tc ~7.4 K.

Superconducting properties are pressure-dependent, with Tc decreasing under pressure.

Epitaxial growth strategy can enhance Tc in titanium oxide systems.

Abstract

Titanium oxides have many fascinating optical and electrical properties, such as the superconductivity at 2.0 K in cubic titanium monoxide TiO polycrystalline bulk. However, the lack of TiO single crystals or epitaxial films has prevented systematic investigations on its superconductivity. Here, we report the basic superconductivity characterizations of cubic TiO films epitaxially grown on (0001)-oriented Al2O3 substrates. The magnetic and electronic transport measurements confirmed that TiO is a type-II superconductor and the record high Tc is about 7.4 K. The lower critical field (Hc1) at 1.9 K, the extrapolated upper critical field Hc2(0) and coherence length are about 18 Oe, 13.7 T and 4.9 nm, respectively. With increasing pressure, the value of Tc shifts to lower temperature while the normal state resistivity increases. Our results on the superconducting TiO films confirm the strategy to achieve higher Tc in epitaxial films, which may be helpful for finding more superconducting materials in various related systems.